One of the fundamental questions facing development biologist is how a multi-cell organism develops from a fertilized egg, a totipotent stem cell, which contains a simple symmetrical structure, into an adult, which has a three-dimensional body plan. Dysregulation of this process results in aborted embryogenesis during early development and frequently results in tumor formation in adult life. There is a need for agents and methods for regulating the development process and treating various disorders related to dysregulated development, such as cancers, degenerative diseases, and immune disorders.
The Wnt signaling pathway is involved in the proliferation or differentiation of various stem cells. For example, it plays essential roles in the differentiation of hematopoietic stem cells derived from fetal tissue or bone marrow. Bone morphogenic proteins (BMPs) belong to the TGF-β super family and are found in species ranging from flies to mammals. The BMP signal pathway is important in cell fate determination and pattern formation during embryogenesis and in the maintenance of tissue homeostasis in the adult. The BMP pathway is also involved in regulation of morphogenesis and postnatal regeneration of GI development. See, e.g., U.S. Pat. Nos. 6,824,971, 6,159,462, 6,465,249, and 6,165,748.